姜黄素通过HO/GC途径对抗高糖诱导的血管收缩功能下降

目的:研究姜黄素是否可对抗高糖诱导的血管收缩功能下降,并探讨其作用机制。方法:采用血管环离体灌流装置,观察SD大鼠胸主动脉环的收缩反应;测定主动脉胆红素生成量反映血红素加氧酶-1(HO-1)的活性。结果:(1)与空白对照组(含11mmol/L葡萄糖)相比,经44mmol/L葡萄糖(高糖)孵育血管4h后,主动脉环对苯肾上腺素(PE)引起的血管收缩反应下降;(2)姜黄素(3×10-11-3×10-10mol/L)与高糖联合孵育,均能不同程度地抑制高糖诱导的血管PE收缩反应的下降;(3)姜黄素孵育后可引起血管HO活性增高;HO-1抑制剂锌原卟啉Ⅸ(ZnPP)可完全取消姜黄素的抗高糖损伤作用;(4)鸟苷酸环化酶(GC)抑制剂亚甲蓝可部分阻断姜黄素的保护作用。结论:姜黄素可能通过诱导HO-1活性增加和激活GC途径对抗高糖引起的血管收缩功能降低。     

Mutations in DDHD1, encoding a phospholipase A1, is a novel cause of retinopathy and neurodegeneration with brain iron accumulation

Defects of phospholipids remodelling and synthesis are inborn errors of metabolism responsible for various clinical presentations including spastic paraplegia, retinopathy, optic atrophy, myo- and cardiomyopathies, and osteo-cutaneous manifestations. DDHD1 encodes a phospholipase A1, which is involved in the remodelling of phospholipids. We previously described a relatively pure hereditary spastic paraplegia (HSP) phenotype associated with mutations in DDHD1. Here we report a complex form of HSP associated with retinal dystrophy and a pattern of neurodegeneration with brain iron accumulation (NBIA) on brain MRI, due to a novel homozygous mutation in DDHD1. This observation enlarges the clinical spectrum of DDHD1-associated disorders and sheds light on a new aetiology for syndromes associating retinopathy and NBIA. It also emphasizes the role of complex lipids in the retina.     

A stress-induced, superoxide-mediated caspase-1 activation pathway causes plasma IL-18 upregulation

Psychological/physical stresses are known to cause relapses of autoimmune and inflammatory diseases. To reveal a mechanism by which noninflammatory stresses affect host defenses, responses to immobilization stress in mice were investigated, focusing on the role of a multifunctional cytokine, interleukin-18 (IL-18). In the adrenal cortex, the stress induced IL-18 precursor proteins (pro-IL-18) via adrenocorticotropic hormone (ACTH) and a superoxide-mediated caspase-1 activation pathway, resulting in conversion of pro-IL-18 to the mature form, which was released into plasma. Inhibitors of caspase-1, reactive oxygen species, and P38 mitogen-activated protein kinase (MAPK) suppressed stress-induced accumulation of plasma IL-18. These inhibitors also blocked stress-induced IL-6 expression. This, together with the observation that IL-6 was not induced in IL-18-deficient mice, showed that IL-6 induction by stress is dependent on IL-18. In stressed organisms, IL-18 may influence pathological and physiological processes. Controlling the caspase-1 activating pathway to suppress IL-18 levels may provide preventative means against stress-related disruption of host defenses.     

Curcumin induces heme oxygenase 1 through generation of reactive oxygen species, p38 activation and phosphatase inhibition

Curcumin is a naturally occurring compound which is known to induce heme oxygenase 1 (HO-1), although the underlying mechanism has not been fully elucidated. This study investigates in detail the mechanism of HO-1 induction by curcumin in human hepatoma cells. There was increasing toxicity of curcumin at concentrations higher than 10 microM. Curcumin was found to induce HO-1 at doses of 10 to 25 microM. At both non-toxic and toxic doses, HO-1 induction was found to correlate with production of reactive oxygen species (ROS), suggesting a causative relationship. This was reinforced by the finding that pretreatment with the antioxidants N-acetylcysteine, vitamin E and catalase prevented HO-1 induction by curcumin. ROS production appeared to be mitochondrial in origin, and curcumin treatment resulted in depolarisation of the mitochondrial membrane potential. Nrf2 was induced by curcumin treatment, which was also partly ROS dependent. Using siRNA, Nrf2 was demonstrated to contribute to HO-1 induction. A panel of kinase inhibitors was used to examine the contribution of MAP kinases to the induction of HO-1 by curcumin. PKC and p38 MAPK activity are required for full induction of HO-1. Furthermore, curcumin also inhibited protein phosphatase activity. In conclusion, curcumin treatment results in ROS generation, activation of Nrf2 and MAP kinases and the inhibition of phosphatase activity in hepatocytes, and when curcumin is not administered in toxic doses, these multiple pathways converge to induce HO-1.     

Targeting mitochondrial dysfunction: role for PINK1 and Parkin in mitochondrial quality control

Mitochondria, which convert energy for the cell, accumulate damage with age, and the resulting mitochondrial dysfunction has been linked to the development of degenerative diseases and aging. To curb the accumulation of damaged mitochondria, the cell has elaborated a number of mitochondrial quality control processes. We describe recent work suggesting that Parkin and PTEN-induced putative kinase 1 (PINK1), two gene products linked to familial forms of parkinsonism, may constitute one of the cell's mitochondrial quality control pathways-identifying impaired mitochondria and selectively trimming them from the mitochondrial network by mitophagy. In particular, we discuss the regulation of PINK1 protein expression and Parkin localization by the bioenergetic status of individual mitochondria; the mechanism by which PINK1 recruits Parkin to the outer mitochondrial membrane; and Parkin's promotion of mitophagy through its ubiquitination of outer mitochondrial membrane proteins. This recent work suggests that Parkin and PINK1 may be among the first mammalian proteins identified with a direct role in regulating mitophagy, and implicate a failure of mitophagy in the pathogenesis of Parkinson's disease.     

Adenosine effectively restores endotoxin-induced inhibition of human neutrophil chemotaxis via A1 receptor-p38 pathway

Neutrophil chemotaxis plays an essential role in recruiting neutrophils to sites of inflammation. Neutrophil chemotaxis is suppressed both after exposure to lipopolysaccharide (LPS) in vitro and during clinical and experimental endotoxemia, leading to serious consequences. Adenosine (ADO) is a potent anti-inflammatory agent that acts on a variety of neutrophil functions. However, its effects on human neutrophil chemotaxis during infection have been less well characterized. In the present study, we investigated the effect of ADO and its receptor-specific antagonist and agonist on neutrophil chemotaxis in an in vitro LPS-stimulated model. The results showed that increasing the concentration of ADO effectively restored the LPS-inhibited neutrophil chemotaxis to IL-8. A similar phenomenon occurred after intervention with a selective A1 receptor agonist but not with a selective antagonist. Pre-treatment with cAMP antagonist failed to restore LPS-inhibited chemotaxis. Furthermore, protein array and western blot analysis showed that the activation of A1 receptor significantly decreased LPS-induced p38 MAPK phosphorylation. However, the surface expression of the A1 receptor in LPS-stimulated neutrophils was not significantly changed. Taken together, these data indicated that ADO restored the LPS-inhibited chemotaxis via the A1 receptor, which downregulated the phosphorylation level of p38 MAPK, making this a promising new therapeutic strategy for infectious diseases.     

Yersinia pestis TonB: role in iron,heme, and hemoprotein utilization

In Yersinia pestis, the siderophore-dependent yersiniabactin (Ybt) iron transport system and heme transport system (Hmu) have putative TonB-dependent outer membrane receptors. Here we demonstrate that hemin uptake and iron utilization from Ybt are TonB dependent. However, the Yfe iron and manganese transport system does not require TonB.     

Regulation of heme metabolism during senescence: activity of several heme-containing enzymes and heme oxygenase in the liver and kidney of aging rats

The activities of several heme-containing enzymes plus succinate dehydrogenase, the content of mitochondrial cytochromes, the amount of microsomal cytochrome P-450, and the activity of heme oxygenase, the major enzyme of heme degradation, have been compared in young, mature and senescent rats. Measurements were made in liver, a tissue previously reported to have an age-related decrease in δ-aminolevulinic acid synthetase, and in kidney, a tissue previously reported to have no age-related change in this enzyme, the rate-limiting enzyme of heme biosynthesis (Paterniti, Lin and Beattie, Arch. Biochem. Biophys., 191 (1978) 792–797). The activity of cytochrome oxidase in liver mitochondria did not decrease with age while this activity in kidney mitochondria was highest in animals one year old and decreased in the two-year-olds. By contrast, succinate dehydrogenase of both kidney and liver mitochondria decreased markedly in the aging rats. No age-related change in the content of cytochromes b, c or aa₃ was observed in liver mitochondria; however, a marked age-related decrease in cytochrome aa₃ was observed in kidney mitochondria. Similarly no change in cytochrome P-450 levels was observed in either tissue obtained from aging animals. In the liver, catalase activity increased while in the kidney it decreased in senescent as compared to mature animals. Heme degradation does not decrease with age as the activity of heme oxygenase increased in both liver and kidney of two-year-old rats as compared to one-year-olds. These results suggest that the lower activity of δ-aminolevulinic acid synthetase observed in the aging rat may not be correlated with a decrease in the activity of heme-containing proteins and that the regulation of the heme pool used for the synthesis of various intracellular hemo-proteins may be complex.     

Heme, heme oxygenase, and ferritin: how the vascular endothelium survives (and dies) in an iron-rich environment

Iron-derived reactive oxygen species are involved in the pathogenesis of numerous vascular disorders. One abundant source of redox active iron is heme, which is inherently dangerous when it escapes from its physiologic sites. Here, we present a review of the nature of heme-mediated cytotoxicity and of the strategies by which endothelium manages to protect itself from this clear and present danger. Of all sites in the body, the endothelium may be at greatest risk of exposure to heme. Heme greatly potentiates endothelial cell killing mediated by leukocytes and other sources of reactive oxygen. Heme also promotes the conversion of low-density lipoprotein to cytotoxic oxidized products. Hemoglobin in plasma, when oxidized, transfers heme to endothelium and lipoprotein, thereby enhancing susceptibility to oxidant-mediated injury. As a defense against such stress, endothelial cells upregulate heme oxygenase-1 and ferritin. Heme oxygenase opens the porphyrin ring, producing biliverdin, carbon monoxide, and a most dangerous product-redox active iron. The latter can be effectively controlled by ferritin via sequestration and ferroxidase activity. These homeostatic adjustments have been shown to be effective in the protection of endothelium against the damaging effects of heme and oxidants; lack of adaptation in an iron-rich environment led to extensive endothelial damage in humans.     

大鼠缺氧性肺动脉高压过程中缺氧诱导因子1α和血红素氧合酶1的变化

目的：观察缺氧大鼠肺小血管壁缺氧诱导因子1α（HIF-1α）和血红素氧合酶1（HO-1）基因表达。方法： 40只雄性Wistar大鼠随机分成缺氧0、3、7、14和21 d组。测平均肺动脉压（mPAP），血管形态学指标，右室肥大指数(RVHI)，HO-1活性和HIF-1α, HO-1 基因表达。结果： 缺氧7 d mPAP高于对照组，缺氧14 d达到高峰并维持于此水平。肺血管重塑，RVHI改变在缺氧14 d后出现。HIF-1α蛋白在对照组表达不明显，各缺氧组血管内膜均为阳性。在中膜，HIF-1α蛋白缺氧3 d开始增高，第7 d达到高峰，14 d和21 d后下降，HIF-1α mRNA缺氧14 d增高, 此后维持于高水平。HO-1蛋白在缺氧7 d后增高，14 d后达到高水平，并持续于高水平。HO-1 mRNA缺氧3 d增高，7 d达高峰，之后下降。结论： HIF-1α和HO-1 均在大鼠缺氧性肺动脉高压的发病机制中发挥作用，且HIF-1α与HO-1基因表达可能有相互调控。     

Heme, iron, and the mitochondrial decay of ageing

Heme, the major functional form of iron, is synthesized in the mitochondria. Although disturbed heme metabolism causes mitochondrial decay, oxidative stress, and iron accumulation, all of which are hallmarks of ageing, heme has been little studied in nutritional deficiency, in ageing, or age-related disorders such as Alzheimer's disease (AD). Biosynthesis of heme requires Vitamin B(6), riboflavin, biotin, pantothenic acid, and lipoic acid and the minerals zinc, iron, and copper, micronutrients are essential for the production of succinyl-CoA, the precursor for porphyrins, by the TCA (Krebs) cycle. Only a small fraction of the porphyrins synthesized from succinyl-CoA are converted to heme, the rest are excreted out of the body together with the degradation products of heme (e.g. bilirubin). Therefore, the heme biosynthetic pathway causes a net loss of succinyl-CoA from the TCA cycle. The mitochondrial pool of succinyl-CoA may limit heme biosynthesis in deficiencies for micronutrients (e.g. iron or biotin deficiency). Ageing and AD are also associated with hypometabolism, increase in heme oxygenase-1, loss of complex IV, and iron accumulation. Heme is a common denominator for all these changes, suggesting that heme metabolism maybe altered in age-related disorders. Heme can also be a prooxidant: it converts less reactive oxidants to highly reactive free radicals. Free heme has high affinity for different cell structures (protein, membranes, and DNA), triggering site-directed oxidative damage. This review discusses heme metabolism as related to metabolic changes seen in ageing and age-related disorders and highlights the possible role in iron deficiency.     

Fumaric acid dialkyl esters deprive cultured rat oligodendroglial cells of glutathione and upregulate the expression of heme oxygenase 1

Fumaric acid esters (FAE) are currently tested in clinical studies for their potential to treat multiple sclerosis. Since cellular glutathione is involved in the detoxification of xenobiotics and has been reported to form conjugates with FAE, we have analysed the consequences of an application of various FAE to oligodendroglial cells, using the oligodendroglial cell line OLN-93 and oligodendroglia-rich secondary cultures as model systems. In a concentration of 100 μM, dimethylfumarate (DMF) and diethylfumarate (DEF), but not fumarate nor the monoalkyl esters monomethylfumarate or monoethylfumarate, almost completely deprived both OLN-93 cells and secondary oligodendroglial cultures within 60 min of their cellular glutathione. None of the FAE applied compromised cell viability, nor did a treatment with DMF or DEF cause any extracellular accumulation of glutathione. Half-maximal effects on the cellular glutathione content of OLN-93 cells after 60 min of incubation were observed in the presence of 10 μM DMF or DEF. In contrast, fumaric acid monoalkyl esters had to be applied in millimolar concentrations to decrease the cellular glutathione content significantly within 60 min. After removal of DMF, OLN-93 cells completely restored their cellular glutathione content and strongly upregulated heme oxygenase 1. Thus, alterations in glutathione and heme oxygenase metabolism have to be considered when oligodendrocytes are exposed to fumaric acid dialkyl esters.     

REEP1 mutations in SPG31: frequency, mutational spectrum, and potential association with mitochondrial morpho-functional dysfunction

Hereditary spastic paraplegias (HSP) constitute a heterogeneous group of neurodegenerative disorders characterized at least by slowly progressive spasticity of the lower limbs. Mutations in REEP1 were recently associated with a pure dominant HSP, SPG31. We sequenced all exons of REEP1 and searched for rearrangements by multiplex ligation-dependent probe amplification (MLPA) in a large panel of 175 unrelated HSP index patients from kindreds with dominant inheritance (AD-HSP), with either pure (n = 102) or complicated (n = 73) forms of the disease, after exclusion of other known HSP genes. We identified 12 different heterozygous mutations, including two exon deletions, associated with either a pure or a complex phenotype. The overall mutation rate in our clinically heterogeneous sample was 4.5% in French families with AD-HSP. The phenotype was restricted to pyramidal signs in the lower limbs in most patients but nine had a complex phenotype associating axonal peripheral neuropathy (= 5/11 patients) including a Silver-like syndrome in one patient, and less frequently cerebellar ataxia, tremor, dementia. Interestingly, we evidenced abnormal mitochondrial network organization in fibroblasts of one patient in addition to defective mitochondrial energy production in both fibroblasts and muscle, but whether these anomalies are directly or indirectly related to the mutations remains uncertain.     

Deletion of MCL-1 causes lethal cardiac failure and mitochondrial dysfunction

MCL-1 is an essential BCL-2 family member that promotes the survival of multiple cellular lineages, but its role in cardiac muscle has remained unclear. Here, we report that cardiac-specific ablation of Mcl-1 results in a rapidly fatal, dilated cardiomyopathy manifested by a loss of cardiac contractility, abnormal mitochondria ultrastructure, and defective mitochondrial respiration. Strikingly, genetic ablation of both proapoptotic effectors (Bax and Bak) could largely rescue the lethality and impaired cardiac function induced by Mcl-1 deletion. However, while the overt consequences of Mcl-1 loss were obviated by combining with the loss of Bax and Bak, mitochondria from the Mcl-1-, Bax-, and Bak-deficient hearts still revealed mitochondrial ultrastructural abnormalities and displayed deficient mitochondrial respiration. Together, these data indicate that merely blocking cell death is insufficient to completely overcome the need for MCL-1 function in cardiomyocytes and suggest that in cardiac muscle, MCL-1 also facilitates normal mitochondrial function. These findings are important, as specific MCL-1-inhibiting therapeutics are being proposed to treat cancer cells and may result in unexpected cardiac toxicity.     

Desaturation and heme elevation during COVID-19 infection: A potential prognostic factor of heme oxygenase-1

Increased heme levels, anemia, and desaturation occur during infection. We aimed to compare the levels of heme, heme oxygenase-1 (HO-1), ferritin, and bilirubin in coronavirus disease 2019 (COVID-19) patients at different saturation levels. Heme and HO-1 enzyme levels significantly increased in the low SpO₂ group, but further studies are required.     

ABC transporter-mediated uptake of iron, siderophores, heme and vitamin B12.

Microbes have developed a number of different strategies to utilize iron, which is a vital element for most organisms but not always readily available from the environment. Based on experimental studies and sequence analysis data, this article gives a short overview of ABC transporters related to iron uptake: components of three distinct families mediate the translocation of iron, siderophores, heme and vitamin B12 across the cytoplasmic membrane of bacteria.